Apparatus and process for flashing mineral oils



Dec. 12, 1939. FENsKE AL 2,183,094

APPARATUS AND PROCESS FOR FLASHING MINERAL OILS Original Filed Sept. 13., 1933 2 Sheets-Sheet 1 RICE/VCR E2, 1939. M. R. FENSKE ET AL.

APPARATUS AND PROCESS FOR FLASHING MINERAL OILS ZShets-Sheet 2 Original Filed Sept. 15', 1933 Patented Dec. 12, 1939 UNlTED STATES APPARATUS AND Pnoonss FOR FLASHING MINERAL OILS Merrcll R. Fenske, State College, and Wilbert B.

McCluer, Bradford, Pa, assignors to Pennsylvania Petroleum Research Corporation, a corpcration of Pennsylvania Original application September 13, 1933, Serial No. 689,330. Divided and this application December 19, 1936, Serial No. 116,706

3 Claims.

This invention pertains to the flashing of mineral oils. It is particularly applicable to the fractionation of mineral oils containing both high and low boiling fractions such as an over- 5 all crude oil, although it is also applicable to the fractionation of either high boiling or low boiling portions for instance to the fractionation of bright stock. As is well known, crude oils con-- tain fractions which range all the Way from highly volatile materials (as well as dissolved gases) to materials of very low volatility. In fractionating by way of distillation, considerable difficulty is experienced in vaporizing the high boiling fractions since excessive heat for extended periods must be avoided to prevent cracking. In the usual distillation processes, the fractions are taken off substantially in the order.

total pressure on the oil, orsteam and oil, is

greater than the vapor pressureof the oil.

The use of steam, however, is a mere expedient to effect the application of heat, the turbulence of the oil and the increased vaporization. It has many disadvantages among which are inefficiency in the use of heat energy, contamination of the fractions with water, etc.

The entire process of taking off the fractions in the order of their volatility, or substantially in such order, consumes considerable time and labor, and requires a relatively large amount of equipment, compared to the amount of materials treated per unit of time.

In contrast to the foregoing. and in accordance with this invention, all of the fractions which present in the material to be fractionated are,

50 employed to function in the manner of steam in steam distillation, and the vaporized oil is separated into its fractions by fractional condensation. Steam may be added to assist or supplemerit the action of the more volatile constituents if desired, or desired fractions may be recycled for this purpose, or both may be resorted to, if desired. Low boiling fractions may also be added to the oil before processing if desired, particularly if it is high boiling.

Other features of the invention reside in the construction, arrangement and combinations of parts, and. in the steps and combinations and sequences of steps of. the process, all of which, together with further features, will become apparent to persons skilled inthe art as this specification proceeds,and. upon reference to the accompanying drawings in v which:

Figure l is a diagrammatic illustration of apparatus for carrying, out the above process;

and

Figure 2- is an illustration of a suitable temperature controlfor the condenser sections.

Referring now: more particularly to the drawings which illustrate one embodiment of the invention, at Ill is shown a column adapted for fractional condensation- Column it is particularly designed to effect heat economy and afford fractionation. It is to be understood that other constructions may be employed to serve the fundamental purposes ofthe column illustrated.

Column it is, divided vertically into, a plurality of sections, each section serving to condense and separate one fraction. The sections may be of any number. For the purpose of ilustration, five sections, ll, l2, I3, M and it, have been shown, but are not necessarily intended to be a representative number. Thenumberof sections employed Will depend upon the number of different fractions desired. It is conceivable that the column It may be made with a large number of sections, in which case the number of sections desired for any operation might be selected be-' ginning from the bottom and proceeding upward, leaving the surplus sections at the top inoperative.

Sections H to llihave heat transfer coils it to 20 respectively. These coils are connected in series. tween each pair of coils so that the oil entering each coil may be at the desired temperature. Each temperature control means, as illustrated, comprises, a heat. responsive control member of any suitable type represented generally at 2!, and oil cooling and heating apparatus represented generally at22.

Cooling between coils is provided for since the latent heat liberated upon condensation in any one section, which heat is absorbed by the oil flowing through the coil of that section,

Temperature control means is inserted be-- generally raises the oil to a higher temperature than is ordinarily desired for effective heat absorption in the coil of the next section in the series. Preferably the oil should enter each coil at a predetermined temperature which is determined by the amount of latent heat to be absorbed by the coil to efiect condensation of the desired fraction and the rate of flow of oil through the coil. For a very close out, it might be necessary in some cases to actually heat the oil to bring it to the desired temperature. Therefore, 22 preferably comprises both heating and cooling means as illustrated.

It is preferred that the fraction condensed in any one section shall not reflux into a lower section. Means for taking off a side stream is therelore provided at the bottom of each section. This means has been represented as a plate 24 of the bubble cap type in each section with a draw 01f pipe 215, although any means which would collect all of the condensate, and yet permit the upward now of uncondensed vapors, may be employed. Draw-off pipe is positioned so as to keep the plate 2 eifectively drained to any suitable level so as to prevent the condensate from overflowing into the next lower section.

If desired, scrubbing may take place within the sections. Means for this purpose has been diagrammatically represented in each section as a plate 26 but any effective means for this purpose may be employed. It is obvious that any desired number of theoretically perfect plates may be employed in each section and that plate 24 might also be employed for scrubbing purposes.

The crude, bright stock or other oil enters the coil it of the upper section at 28 and after flowing therethrough, is brought to the desired temperature prior to entering the coil I! of the next lower section. The same is true of the oil that leaves any one section and before it enters the next. The oil is finally delivered in a pre-heated condition from the coil of the lowermost section, represented as 20.

The use of the oil to be processed, whether it is crude, bright stock, or other oil, in the coils Hi to 20 for the purpose of absorbing heat from the ascending vapors to cause selective condensation in the individual sections, is for the purpose of heat conservation, for in this way such oil is delivered to the first pipe still 34 in a pre-heated condition. Any other suitable means might therefore be substituted for this preheating arrangement provided, of course, that the desired results are obtained.

The oil to be processed flows preferably continuously and preferably under elevated pressure through pipe still 35, whether preheated or not, and is rapidly heated therein to a relatively high temperature. The temperature to which the oil is heated in still 34 need not exceed a safe noncracking temperature, but since cracking not only involves heat and/or pressure but also time, it is preferred that the oil be heated to a higher temperature and that the time of heating be kept below that which would effect cracking. This time interval decreases with rise in temperature as is well known in the art. The limit in the temperature to be employed for any one type or oil is therefore conditioned upon the time required for the oil to flow from the point where it reaches a cracking temperature to the point where it is brought back to below a cracking temperature, upon the rate of temperature rise in the oil, the highest temperature reached and the rate of cooling of the oil. The latter point will be more fully described hereinafter.

The oil is preferably maintained in still 34 under a sufficiently elevated presstu'e to keep as much of the oil as possible in the liquid phase and to keep that portion of the oil which may be in the vapor phase of a relatively high density. Under these conditions separation of the low boiling constituents is maintained at a minimum. It is preferred to avoid substantial separation in order that the relatively volatile portions may more intimately contact and bubble through the less volatile portions and bring about to a greater degree the desired effects which result from the use of steam distillation processes.

The pressure in still 36 may be brought about by any suitable means. As illustrated, a high pressure pump 35 is provided at the inlet of still 34 and a constricted portion 36, represented as an expansion valve, is provided at has outlet. To maintain the pressure in still 34 more or less constant, valve 36 may be made to respond to pressure, opening slightly further when the pressure exceeds the desired value and closing slightly when the pressure falls below each value. Any suitable device may be employed for this purpose. Valve 36 may be operated manually to control the pressure in a similar manner, and gauge 37 may be provided to guide the manual operation of valve 36.

The pressure on the oil is released as it passes through valve 36. In view of the high temperature of the oil the highly volatile constituents immediately vaporize and expand carrying with them the less volatile portions.

The entire mass is preferably carried first through pipe still 38 before entering chamber 3|. Pipe still 38 is preferably designed as to the diameter of its tubes taking into consideration the rate of fluid flow so as to cause considerable turbulence in the material passing therethrough.

The highly volatile material boils through the material of low volatility much the same as steam boils through the oil in steam distillation. The result is a substantially increased vaporization due to the increased vapor volume formed by the vaporization of the low boiling materials.

The vaporized and non-vaporized materials flow from still 38 to chamber 3| through pipe 380. and separate in chamber 3i. pass up through the bottom 35) of the lowest section of column ID. From this point on up through column iii fractional condensation takes place, the fractions condensing successively in successive sections in the reverse order of their volatility.

Once the desired portions of the oil are vaporized it becomes a relatively simple matter to separate them into fractions by the means previously described.

The non-vaporized portion which is dropped in chamber 3| contains a large proportion of those materials which are responsible for color and the formation of carbon. The percentage of nonvaporized material is a matter for choice. It may be relatively small or may for instance be sufficient to correspond to a cylinder stock.

As the oil passes through valve 36 it begins to cool due to the heat absorbed by vaporization. If the oil were heated as it passed through still 34 to a point above a safe non-cracking temperature it would eventually in cooling, return to a safe non-cracking temperature. The highest temperature to which any particular type of oil The vapors may be heated in still 34 may be determined by actual trial of the equipment or by calculation. The rate of travel of the oil through still 34,

, the design of still 34, and the type of material which cracking might occur.

The highest safe non-cracking temperature will of course vary with each type of oil as is well known. It will generally correspond to the limit in temperature employed in an ordinary distillation process for the particular mineral oil;

As the material passes through still 38 more and more vapor is formed and more and more latent heat is absorbed. In order to bring more of the materials of low Volatility into the vapor phase, heat may be added to the vaporizing oil in still 38 to compensate for that absorbed. The heating in still 38 is not intended to bring the materials above a safe non-cracking temperature, unless of course the rate of travel of the oil is so great that the safe time interval above referred to is not exceeded before the material is finally released into chamber 31 and suihciently cooled by vaporization therein, in which case this could be done, if desired.

Considered broadly still 38 is to be regarded as a heat transfer device for the purpose of controlling the temperature of the vapors and liquid passing therethrough. It might therefore actually have cooling means for instance to assure a non-cracking temperature.

When the material is delivered to chamber 35, the non-volatile portions are dropped along with the non-vaporized, relatively non-volatile portions. If desired, means for dispersing the material' such as a closed drum 35a upon the surf face of which the material impinges after leaving pipe 38a may be provided.

In the event that it is desired to increase the effects of the highly volatile constituents ofthe oil, or if the oil is deficient in highly volatile portions andan increased effect is desired, one

or more of the lower boiling fractions may be recycled by adding them to the fresh oil. Means for this purpose is illustrated diagrammatically in the drawings.

At 40 is shown a tap on draw-off pipe 25 of top section I I towhich is connected pipe H in which turn is connected to the inlet of pump" By this means any desired portion of this fraction may be recycled, valve 32 in pipe ii affording a control for this purpose.

A similar tapis shown at $3 on draw-off pipe 25 of the next lower section [2, which is connected to the inlet of pump 35 through pipe 46 and pipe d1, valvetii in pipe 4d affording a control of the amount of this fraction to be re-' cycled.

.Similar arrangements may be made for recycling the condensate from any desired section. If. one or more lower boiling fractions have been added to higher boiling material, for in stance, a gas oil or lower fraction to bright stock,

prior to processing to obtain the desired effects accruing therefrom during processing, these lowor boiling fractions may be continuously recycled,

thus making it unnecessary to continue to add "such lower boiling materials to the higher boilvalve t ing material, except to makeup for unavoidable losses.

The column it] may operate at atmospheric,

super-atmospheric or at reduced pressures. Reduced pressures would of course facilitate the vaporization of the higher boiling constituents.

Reduced pressures would generally be preferredto'assist or supplement the more volatile materials. is illustrated diagrammatically in. the drawings. header, 52 a pipe leading to the inlet of still 3d and 53 a control valve in pipe 52. 5 2 represents a pipeleading from header 55 to; the downstream side of valve 36. Steam flow is controlled by a 55 represents a pipe leading from head er ti o the outlet of still 38 and 5 7 is a control valve n. said pipe. 58 represents a pipe leading from header 5! to and into the chamber 3!. Flow through pipe 58 is controlled by valve to. l The point at wniclzi the steam enters the systern depends l st of all upon the temperature of the steam; If the temperature of the steam is less than that of the oil leaving still t l, it will,

generally be introduced into still 34 through oipe 52 so avoid reducing the oil tempera- Water might be used in place of steam in which case it would be introduced at this point. Steam, regardless of temperat re, might be introducedinto still 3 5 to'get the eifect of steam passing through valve 3-6 along with the oil. 01', the steam may be introduced on the downstream side of valve 33 through pipe 5d, particularly if it is at the same temperature or is of a higher temperature than the oil, unless perchance a quicker cooling is desired to avoid cracking. The steam may also be introduced through pipes 5% or 58 which is substantially the same except that pipe 58 directs the steam upward in chamber The connection 38a between the outlet of still 38 and the chamber 3| quired to cause the oil to flow at the desired rate with valve 38 wide open or eliminated, to

that which is required to keep all fractions in the liquid phase, except th se which have reache their critical temperatures.

Furthermore, while the use of pipe still 35 for the purpose of causing turbulence and/or for heat transfer is preferred, the outlet of still 3 3 might directly to chamber iii in the bottom of column ill, with or without the use of valve To obtain the benefits of a degree of subdivision of the heated oil as it passes out of still 34!, whether it goes directlyto chamber 3i or by way of still 38, an atomization of the oil maytake place. Valve 3%, for instance, may be of represents a steam source, 5! a an atomizing type, or atomizing means may be provided at the inlet to chamber 3|. Valve 36 might be used for the latter purpose when still 38 is not employed. Or atomization at both points may be provided for if still 33 is employed, but preferably without an appreciable increase in pressure drop between the outlet of still 38 and the inlet of chamber 3!.

While the invention has been described in connection with the processing of oils, it is to be understood that it is applicable to the fractionation of any other materials, particularly where similar problems are involved.

The temperature control means at 2! and 22 may obviously be of any suitable character known in the art. In Figure 2 for instance is schematically illustrated such a control which will be considered as being inserted between coils i6 and I1. Pipe 6| leads from coil is and connects to heating means (52 comprising a coil 83 for the oil and a chamber 64 for steam for heating coil 63. An electrically controlled valve 65 controls the flow of steam into chamber $4, said valve being opened when current flows through solenoid 66 thereof. Solenoid 65 is in a circuit comprising battery 6? and relay 68. Relay 68 is normally open so that valve 65 is normally closed.

Coil 63 of heater 62 is connected in series with coil 10 of cooler ll.

Coil 1B is surrounded by a chamber (2 for cooling water. The fiow of water through chamber 12 is controlled by an electrically controlled valve 73, said valve being opened when current flows through the solenoid l4 thereof. Solenoid M is in a circuit which comprises battery 15 and relay ?6. Relay T5 is normally open so that valve 13 is normally closed.

A temperature gauge 13 is connected in pipe 79 which leads from coil ill to coil ll. Gauge '58 has an indicator 80 which registers on a dial 8i, said indicator moving clockwise with increase in temperature and counter-clockwise with decrease in temperature.

A contact 32 is adjustably supported at 83 and may be placed opposite any desired point on dial 8|. Contact 82 is contacted by indicator ill to close a circuit through relay 68, when the temperature of the oil falls below a desired point. This opens steam valve 65. permitting steam to enter chamber 62 to heat the oil flowing through coil 63. As soon as the desired temperature is restored, valve 55 will close because of the opening of relay 68. This opening of relay 63 is caused by indicator 80 leaving contact 82. The cycle is repeated when the temperature of the oil falls below the desired value.

A second contact 8-:- is adjustably supported at 85 in a similar manner. Contact 85 is contacted by indicator 8!] to close a circuit through relay 16 when the temperature of the oil exceeds a desired point. This opens valve i3 and permits water or other refrigerant to flow through chamber 12 to cool the oil flowing through coil 752. As soon as the desired temperature of the oil is restored, valve l3 closes because of the breaking of the circuit through relay .6. This circuit is broken when indicator 8Q leaves contact 84. The cycle is repeated when the temperature of the oil again exceeds the desired value.

Current for the operation of relays 63 and i6 is supplied by battery 8%. Any other suitable arrangement may be provided.

The fractions and bottoms are of course preferably collected in individual receivers. This is illustrated in the drawings in which 88, 89, 9B, 9!

and 92 are individual receivers for sections 1 l to I5 respectively and 93 is a receiver for the bottoms. The receivers are, of course, preferably operated at the same pressure as the column, as is well understood in the art.

The apparatus particularly described and exemplified in the drawings is of the continuous type. The invention may be likewise applied to batch operation. Suitable apparatus therefore will occur to persons skilled in the art upon becoming familiar with this invention.

While in the above description it is contemplated that the oil shall reach its highest, or in other words, final temperature in still 34, if desired, and provided still 38 has sufficient heat transfer capacity, the highest temperature may actually be reached in still 38.

Although the vapors produced are preferably fractionally condensed since they are recovered in an excellent condition for this purpose, they may be condensed as a whole, the net result of which will be the separation of the condensate from the residue.

A single embodiment of the invention has been described for the purpose of illustration. It is therefore to be understood that changes, emissions, additions, substitutions and modifications may be made without departing from the spirit thereof, or avoiding the scope of the claims which are intended to be limited only as required by the prior art.

While the invention has been more particularly described in connection with relatively non-volatile materials mixed with volatile materials it is to be understood that it may be applied to any mixture which is separated by fractional distillation whether such a mixture is in the vapor, liquid or solid phase at atmospheric pressure and ordinary temperatures.

Any of the parts used in connection with the still 38 may also be constructed so as to cause turbulence of the fluids flowing therethrough and the dispersing means represented at am in chamber 35 may have any desired construction. It will be understood that any devices and constructions known in the art may be employed for carrying out the invention and it will of course be obvious that heat insulation will be employed where desired.

In separating given materials either elevated or reduced pressure might be used to take advantage of different temperature slopes of the vapor pressure curves at different pressures.

This application is a division of our (Jo-pending application 689,330 filed September 13, 1933, now United States Patent No. 2,067,627.

We claim:

1. Apparatus for fractionating a liquid mixture such as mineral oil comprising, a plurality of serially arranged sections adapted to permit the fiow of vapors consecutively therethrough, condensing coils in each section, means for conducting a constant rate or" supply of feed liquid serially through said condensing coils of said secticns as a heat exchange medium, said feed liquid flowing countercurrently to but in indirect contact with said vapors, means for controlling the heat exchange capacity of said constant rate of supply of feed liquid in each coil independently of the heat exchange capacity of said feed liquid in the other coils, means for further heating said feed liquid after leaving the last condensing coil, a vaporizing chamber connected to one end of said series of sections in a manner to deliver vapors thereto, means for connecting said heating means to said vaporizing chamber to deliver heated materials thereto, and means for separately withdrawing condensate from each of said sections.

2. Apparatus for fractionating a mineral oil, comprising a column, a plurality of vertically arranged sections in said column adapted to permit the upward flow of vapors, an individual condenser in each section, each condenser having cooling means adapted to conduct a cooling liquid, scrubbing means for each section positioned beneath the condenser thereof, means in each section beneath said scrubbing means for withdrawing the total condensate from said section, means for conducting a constant volume of said mineral oil at a constant rate serially through said condensers as a cooling liquid from top to bottom of said column, means at the inlet of each condenser for controlling the temperature of said oil, means for heating said oil under relatively high pressure, means for heating said oil under relatively lower pressure, means for finely subdividing said oil between said first and second mentioned means, means for conducting said oil, after leaving said condensers, through said first mentioned heating means at a relatively high pressure, through said subdividing means, then through said second mentioned heating means at a relatively lower pressure to the bottom of said column, an expansion chamber for said oil at the bottom of said column, said chamber adapted to permit the non-vaporized portions of said oil to separate from the vaporized portions by gravity, and to permit the vaporized portions to pass up through said sections, and means at the bottom of said chamber for removing said non-vaporized portions.

3. A continuous process for the fractionation of a mineral oil comprising, continuously heating a stream of oil to a cracking temperature while maintaining said oil substantially homogeneous by subjecting said oil to a pressure sufficiently high to maintain at least substantially all of said oil in the liquid phase and any component which may have reached its critical temperature at a relatively high density, continuously projecting the heated oil after reaching a cracking temperature but before any substantial cracking thereof takes place into a restricted sphere of vaporization to reduce the temperature of said oil sufliciently to avoid cracking, thoroughly mixing the vapor thus produced with the remaining liquid as said vapor and liquid fiow through said restricted sphere, then projecting said mixed vapor and liquid into an unrestricted sphere of vaporization, conducting vapors from said unrestricted sphere serially through a plurality of condensing zones, conducting said stream of oil in its entirety and at a constant rate prior to said first-mentioned heating serially through said condensing zones countercurrently to and in heat exchange relationship with but out of direct contact with said last-mentioned vapors, and controlling the condensing effect of said feed oil in individual condensing zones by controlling the temperature of said feed oil in each individual condensing zone individually of the other zones.

MERRELL R. FENSKE. W'JLBERT B. MCCLUER. 

